The present invention relates generally to welding systems, and more particularly, to apparatus for feeding welding wire in welding systems.
An important part of welding systems is the mechanism that feeds an electrode wire, a filler-material wire, or other weld wire to the work piece. Weld wires range in size and in material composition. Typically, weld wires range in size from approximately 0.023 inch in diameter to approximately 0.052 inch in diameter and can be as large as approximately 0.250 inch in diameter, and include material compositions of steel, stainless steel, aluminum, and/or other materials.
As used herein, the phrase “wire feeder assembly” includes a spool of weld wire, a drive assembly, any gun liner, and any other support or control apparatus along the path of travel of the wire between the spool and the contact tip of the gun, including the electronic controls.
Wire feeder assemblies generically comprehend electrode wire feeders used in e.g. Gas Metal Arc Welding (GMAW) in which the electrode wire is fed as part of the welding circuit and melts to become part of the weld deposit/pool. Wire feeder assemblies also include cold wire feeders used in e.g. Gas Tungsten Arc Welding (GTAW) and laser welding in which the filler-material wire is fed into, and melts from the heat of, the weld pool and thus becomes part of the weld pool.
In addition, wire feeder assemblies and/or components thereof can be used to drive materials other than weld wire, such materials typically having generally physically similar characteristics and/or properties to those of weld wire.
The drive assembly typically includes an electric motor which drives a rotationally-driven drive roll, which cooperates with a corresponding pressure roll. Both the rotationally-driven drive roll and the pressure roll, e.g. a pressure drive roll, cooperate in driving the weld wire. The rotationally-driven drive roll and the pressure drive roll have outer circumferential surfaces, at least one of the drive roll and pressure drive roll having a groove formed therein sized and configured to accept a weld wire having a particular diameter, between the cooperating drive rolls.
The pressure drive roll applies lateral pressure against the weld wire and correspondingly against the rotationally-driven drive roll. When the electric motor is energized, it rotationally drives the rotationally-driven drive roll which, in cooperation with the pressure drive roll, advances the weld wire through the liner and contact tip in the welding gun, and into the weld pool.
The drive assembly can jam if the weld wire strays from the desired feed path which extends through the e.g. nip which is defined between the upper and lower drive rolls. Wire jams can be caused when the weld wire collapses as the compressive columnar strength of the weld wire is exceeded, whereupon the weld wire becomes bunched up, tangled, wrapped around drive rolls, or other components in the drive assembly, or otherwise travels along a non-desired path or deviates from the desired path. In any case, such deviant wire travel is sometimes referred to as e.g. “bird's nesting.”
“Bird's nesting” normally occurs in an area in which the weld wire is unsupported, and typically happens when the weld wire drag, or resistance to movement through the liner, combines with the weld wire driving force applied by the drive rolls to overcome the columnar strength of the wire. When the columnar strength is exceeded, the weld wire ceases movement through the conduit, and piles up in the area of collapse, or travels along a non-desired path until the electric motor driving the drive rolls ceases its drive action.
“Bird's nesting” consumes operator/user time, requiring such operator/user to open the drive assembly and to untangle and/or otherwise clear the wire jam, and re-feed the weld wire along the wire drive path.
It is not desirable to have an operator/user opening the drive assembly more often than necessary, as many welding operations are performed in rather harsh environments and dirt and/or other debris frequently found in such welding environments can eventually become lodged in e.g. the liner of the weld gun, which further compromises the travel of the weld wire to the workpiece.
When a wire jam occurs, the weld wire does not advance through the liner and contact tip of the welding gun. Thus the weld wire which extends beyond the contact tip is consumed without a new portion of the weld wire advancing to replace the consumed portion. This phenomenon is commonly referred to as “burn-back” and can result in the weld wire melting into, and thus becoming welded to, the contact tip of the gun. In the event where the weld wire becomes welded to the contact tip, the operator/user typically must install a new contact tip before proceeding with any more welding operations.
As weld wire is advanced along either a desired path e.g. out a welding gun or along a non-desired path such as “bird's nesting,” the weld wire can be energized by a welding power source. Accordingly, if the deviant weld wire comes into electrical contact with e.g. the electric motor of the drive assembly, the integrity of the electric motor can be compromised. Also, since such advancing weld wire is electrically “live,” a weld wire which advances along a non-desired path, for example outwardly of the drive assembly, can pose safety hazards for the operator and/or any persons near such activity.
Some weld wires are generally more susceptible to “bird's nesting” than other weld wires. As one example, aluminum weld wires are more susceptible to traveling along a non-desired path than are steel weld wires because aluminum has a relatively lower columnar strength and a relatively more easily deformable cross section, and/or relatively more malleable.
Numerous approaches of dealing with “bird's nesting” problems in wire feeders have been attempted, including use of TEFLON, and relatively shorter liners in weld guns, and use of weld wire spool guns which are weld guns that house and drive a spool of weld wire in the gun itself rather than having the weld wire spool mounted in combination with a control box. However, it is sometimes desirable to use a weld gun which has a relatively long liner to enable an operator/user to weld at a point relatively distant from the weld wire feeder apparatus. In addition, weld wire spool guns are bulky in comparison to typical weld guns and accordingly can be relatively cumbersome to operate. Further, an operator/user may desire to weld with a spool of weld wire which is larger than that which can be housed in a weld wire spool gun, e.g. it may be desirable to use a 12 inch spool of weld wire instead of a 4 inch spool.
It is desirable, therefore, to improve weld wire feeder assemblies to provide more support for a weld wire in areas of the feeder assemblies in which a weld wire is typically unsupported. In addition, it is desirable to improve weld wire feeder assemblies to provide a relatively more consistent, and relatively more desirably distributed, pressure to a weld wire.
Another problem with typical weld wire feeder assemblies is that service and repair of the drive assembly can be difficult, especially in the field. As one example, weld wire feeder assemblies having two drive mechanisms typically require at least some different components for e.g. left and right drive assemblies, which require storage of corresponding piece-parts for each of the left and right drive assemblies.
As another example of needed improvements, changing drive rolls in some drive assemblies requires tools. Certain known “tool-less” drive assembly designs require a dexterous manipulation of one or more components of the drive assembly.
Therefore, it is also desirable to provide weld wire feeder assemblies which are easily serviced and/or repaired and which have drive assembly components which are common to both left and right drive assemblies, and methods and apparatus which facilitates easy removal and/or changing of drive rolls, other components, or consumable components, without using tools.
It is also desirable to provide drive assemblies which require a cover to be closed over the internal components before operation of the drive assembly, which increases the probability of achieving a relatively clean operational environment within the drive assembly. It is also desirable to provide drive assemblies which have a force converter, for applying a force to a drive assembly, attached to a cover which generally covers components of the drive assembly.
It is also desirable to provide re-designed drive assemblies which impede the development of “bird's nesting,” and which facilitate the travel of the weld wire along the desired path.